Several environmental oestrogens are also anti-androgens

Abstract

There is presently considerable interest in endocrine disruption which is a new area of endocrinology concerned with chemicals that mimic hormones, in particular sex steroids. It has been hypothesised that exposure to such chemicals may be responsible for adverse effects in both humans and wildlife. Until now, chemicals that mimic oestrogens (so-called xenoestrogens) have been the main focus of endocrine disruption research. However, recent evidence suggests that many abnormalities in the male reproductive system may be mediated via the androgen receptor. By blocking androgen action, exposure to an anti-androgen may cause changes similar to those associated with oestrogen exposure.We have used in vitro yeast-based assays to detect oestrogenic, anti-oestrogenic, androgenic and antiandrogenic activities in a variety of chemicals of current interest. We show that many of the so-called 'environmental oestrogens' also possess anti-androgenic activity. The previously reported anti-androgenic activities of vinclozolin and p,p -1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (DDE) were confirmed. We also found that o,p -1,1,1,-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), bisphenol A and butyl benzyl phthalate were anti-androgenic. However, not all xenoestrogens are also anti-androgenic, because nonylphenol was found to be a weak androgen agonist. Our results demonstrate that hormone-mimicking chemicals can have multiple hormonal activities, which may make it difficult to interpret their mechanisms of action in vivo.Although not a specific objective of this study, our results also demonstrate that yeast-based assays are powerful tools with which to investigate both agonist and antagonistic hormonal activities of chemicals.

Screening of multiple hormonal activities in surface water and sediment from the Pearl River system, South China, using effect‐directed in vitro bioassays

“…Hence, antiandrogenic activity is usually prevalent in various environmental matrices as demonstrated in the present and previous studies [39,40]. Another reason for prevalent estrogenic and antiandrogenic activities in the environment could be the wide presence of estrogenic chemicals in surface waters [6,28] and some xenoestrogen chemicals such as bisphenol A and o,p 0 -DDT (o,p 0 -1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) could display both estrogenic activity and antiandrogenic activity in the environment [15].…”

“…The bioassays were carried out as described previously [15]. In summary, a sample extract was diluted by twofold in series, then four aliquots (10 ml for each concentration) were transferred to corresponding wells on four 96-well plates.…”

“…Some xenoestrogens (e.g., 4-nonylphenol, bisphenol-A, and phthalic acid esters) also display weak estrogenic activities and may contribute to the feminization of male fish in the environment [14]. Androgenically active compounds usually contain testosterone, dihydrotestosterone (DHT), and 17a-methyltestosterone [15]. Some natural steroids and their metabolites, such as androsterone, have also been identified as being responsible for the majority of androgenic activity in STP effluents [16], and the synthetic androgens 17a-trenbolone and 17b-trenbolone have been detected in cattle feedlot wastewater [17].…”

“…The fungicide vinclozolin exhibits antiandrogenic activity in rats [22], and some pesticides (e.g., p,p 0 -1,1-dichloro-2,2-bis[pchorophenyl]ethylene [p,p 0 -DDE] and linuron) also show antiandrogenic activities [18]. Furthermore, some pollutants, such as polycyclic aromatic hydrocarbons, in the environment can act as both agonist and antagonist of estrogen or androgen receptors [15,23]. Hence, EDCs are often a complex mixture in environmental matrices and display hormonal effects through multiple action modes on hormone receptors.…”

Assessment of hormonal activities and genotoxicity of industrial effluents using in vitro bioassays combined with chemical analysis

“…All media and strains for assays were prepared according to the original protocol for the YAS [40], and the assay procedure was modified from the procedure for the YES, which was described by Zhao et al [39]. In the YAS assay, dihydrotestosterone (DHT) standard reagent (final concentration: 7 Â 10 À8 M to 5 Â 10 À10 M) was used as the positive control and the methanol as the blank control.…”